Usefulness of 18F-FDG-PET/CT in Therapy Control of Inflammatory and Mycotic Aneurysms

Abstract

Introduction: Mycotic aneurysms (MA) are infectious aneurysms of either the thoracic or the abdominal aorta, whereby the management of mycotic aneurysms carries a high mortality. The aim of the study was to evaluate the usefulness of positron emission tomography/computed tomography with 18F-fluorodeoxyglucose (PET/CT) in the long-term monitoring of patients with proven mycotic or inflammatory aneurysms. Methods: Fifty-seven PET/CT were performed in 16 patients with 15 mycotic and one inflammatory aneurysm (seven patients were prospectively included into the study, nine retrospectively). We quantified the metabolic activity in all aneurysms by using maximum standardized uptake value (SUVmax). We performed clinical follow-up of all patients and recorded patient data at the time of imaging and at the latest clinical visit. Recorded data included laboratory values such as leucocyte count, results of microbiology and other diagnostic procedures, information on patient's treatment and general health condition. Results: Patients were clinically followed for median 1050 days (IQR 704-3187). Endovascular repair was performed in all patients. Two patients (13%) died because of reasons considered not to be directly linked to mycotic or inflammatory aneurysm (one due to gastrointestinal bleeding, the other due to endocarditis). At the last clinical visit, three patients (19%) were on continuous antibiotic or steroid treatment and clinical conditions were stable. One patients (6%) showed recurrent signs of infection at the last clinical visit, which were considered to be due to an infected pancreatic cyst. All other patients (n = 10, 63%) did not show any signs of infection at the last clinical visit and all were without antibiotic or antiinflammatory medication. As compared to the course of C-reactive protein alone, PET/CT provided additional or altering information on the course of disease in at least 14 feasible comparisons (54%) in 11 patients (69%). Median SUVmax measured in the aneurysms at the initial PET/CT was high (7.0 (interquartile range (IQR) 5.9-21.8) and lower at the last PET/CT prior to the end of antibiotic treatment (3.9 (IQR 2.7-6.8; n = 11) as well as in the PET/CT after the end of the treatment (3.9 (IQR 3.0-4.4; n = 6). Conclusion: PET/CT adds additional information in therapy control of inflammatory and mycotic aneurysms, and may have contributed to an excellent clinical outcome in the present study. However, metabolic activity in the aneurysms remains slightly elevated after the end of antibiotic treatment. Disclosure: Nothing to disclose